Subject: [Sigtran] M3UA-v02 Last Call Comment: Maximum SIF deficiency.

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Sat, 8 May 2004 05:09:43 -0600

The draft, as the RFC, has the deficiency that it is not possible for the
MTP3-User at the ASP to discover the Maximum SIF that can be used for the
Data Payload of the DATA message.  This value can be dependent on destination
and will change if an SS7 network reconfiguration change occurs.  Maximum
NIF is similar to IP MTU, but for the SS7 network.  MTP3-Users need to know
its value so that they can properly segment and reassemble MTP-User messages
over MTP MSUs.  Unlike IP, MTP cannot segment (fragment) or reassemble
messages that are too large.  This is the MTP-User's responsibility.  For the
MTP-User to properly segmenet messages it must known the Maximum SIF value.
This value differs for low-speed links, high-speed links, ATM links (and now
M2PA links).  SS7 has rules as to how the maximum value is calculated and
what value is provided to the MTP-User.  There is no MTP interface primitive
for this.

A proposal for a solution to this deficiency was presented some years ago.
See draft-bidulock-sigtran-sginfo-03.txt

M3UA v02 should not proceed without a correction for this deficiency.

--brian

-- 
Brian F. G. Bidulock    ¦ The reasonable man adapts himself to the ¦
[email-masked]    ¦ world; the unreasonable one persists in  ¦
http://www.openss7.org/ ¦ trying  to adapt the  world  to himself. ¦
                        ¦ Therefore  all  progress  depends on the ¦
                        ¦ unreasonable man. -- George Bernard Shaw ¦

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